.NET TextImagifier - Stop kiddies by turning your source into image

Code
'First add a Richtextbox and name it "rtbMain"

'And add a button named "button1"

Imports System.Runtime.InteropServices

Public Class frmMain   

 <DllImport("USER32.dll")> _

    Private Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal msg As Integer, ByVal wParam As Integer, ByVal lParam As IntPtr) As Int32

    End Function

    Public contentRectangle As Rectangle

    Private Const inch As Double = 14.4

    Private Const WM_USER As Integer = &H400

    Private Const EM_FORMATRANGE As Integer = WM_USER + 57

    <StructLayout(LayoutKind.Sequential)> _

    Private Structure RECT

  Public Left As Integer

  Public Top As Integer

  Public Right As Integer

  Public Bottom As Integer

    End Structure

    <StructLayout(LayoutKind.Sequential)> _

    Private Structure CHARRANGE

  Public cpMin As Integer

  Public cpMax As Integer

    End Structure

    <StructLayout(LayoutKind.Sequential)> _

    Private Structure FORMATRANGE

  Public hdc As IntPtr

  Public hdcTarget As IntPtr

  Public rc As RECT

  Public rcPage As RECT

  Public chrg As CHARRANGE

    End Structure



    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

  Dim sfd As New SaveFileDialog

  sfd.Filter = "JPEG Images|*.jpg"

  sfd.Title = "Save as..."

  If sfd.ShowDialog = DialogResult.OK Then

    With rtbMain

    Dim wid As Integer = .Width

    Dim hgt As Integer = .Height

    Dim bm As New Bitmap(wid, hgt)

    rtbMain.DrawToBitmap(bm, New Rectangle(0, 0, wid, hgt))

    RtbToBitmap(rtbMain, contentRectangle, sfd.FileName)

    End With

  End If

    End Sub



    Private Sub RtbToBitmap(ByVal rtb As RichTextBox, ByVal rectangle As Rectangle, ByVal fileName As String)



  Dim bmp As New Bitmap(rectangle.Width, rectangle.Height)

  Using gr As Graphics = Graphics.FromImage(bmp)

    Dim hDC As IntPtr = gr.GetHdc()

    Dim fmtRange As FORMATRANGE

    Dim rect As RECT

    Dim fromAPI As Integer

    rect.Top = 0

    rect.Left = 0

    rect.Bottom = CInt(Math.Truncate(bmp.Height + (bmp.Height * (bmp.HorizontalResolution / 100)) * inch))

    rect.Right = CInt(Math.Truncate(bmp.Width + (bmp.Width * (bmp.VerticalResolution / 100)) * inch))

    fmtRange.chrg.cpMin = 0

    fmtRange.chrg.cpMax = -1

    fmtRange.hdc = hDC

    fmtRange.hdcTarget = hDC

    fmtRange.rc = rect

    fmtRange.rcPage = rect

    Dim wParam As Integer = 1

    Dim lParam As IntPtr = Marshal.AllocCoTaskMem(Marshal.SizeOf(fmtRange))

    Marshal.StructureToPtr(fmtRange, lParam, False)

    fromAPI = SendMessage(rtb.Handle, EM_FORMATRANGE, wParam, lParam)

    Marshal.FreeCoTaskMem(lParam)

    fromAPI = SendMessage(rtb.Handle, EM_FORMATRANGE, wParam, New IntPtr(0))

    gr.ReleaseHdc(hDC)

  End Using

  bmp.Save(fileName, System.Drawing.Imaging.ImageFormat.Jpeg)

  bmp.Dispose()

    End Sub



    Private Sub rtbMain_ContentsResized(ByVal sender As Object, ByVal e As System.Windows.Forms.ContentsResizedEventArgs) Handles rtbMain.ContentsResized

  contentRectangle = e.NewRectangle

    End Sub

End Class